As shown in FIG. 5, a sprinkler nozzle structure of the prior art comprises a nozzle piece 50, a guide seat 60, and a receptacle 70. The guide seat 60 is provided at one end with a fastening portion 61, and at the other end with a tapered portion 63. Located between the fastening portion 61 and the tapered portion 63 is a fitting portion 62. The fastening portion 61 is used to fasten the nozzle piece 50, while the tapered portion 63 is located in the receptacle 70.
Such a prior art nozzle structure as described above is defective in design in that the fitting portion 62 of the guide seat 60 is apt to fit improperly into an outer end 71 of the receptacle 70, and that the tapered portion 63 of the guide seat 60 is susceptible to dislocation, as illustrated in FIG. 6. In light of such deficiencies as described above, the prior art nozzle structure is prone to leak.